Change get_client_managed to return result

[Hinton]

🎟️ Tracking

📔 Objective

Changes get_client_managed to return a Result<_, RepositoryNotFound> based on discussions in #337 (comment)

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation
  team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed
  issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – 47d93d04-6cca-4985-83dd-10eebd4419ee

Great job, no security vulnerabilities found in this Pull Request

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.

Project coverage is 71.70%. Comparing base (0cc1aed) to head (89d53c3).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/bitwarden-core/src/platform/state_client.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #338      +/-   ##
==========================================
- Coverage   71.70%   71.70%   -0.01%     
==========================================
  Files         238      238              
  Lines       19312    19317       +5     
==========================================
+ Hits        13848    13851       +3     
- Misses       5464     5466       +2     

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